Cryptpad:
- Full-on google docs / office365 / libreoffice type replacement with collaboration.
- E2EE
- The complexity means it doesn't work well on mobile, takes a while to load on a slow connection, more frequent bugs. (3.5 MiB page transfer)
- Self-hosting is complicated.
Etherpad:
- A competent collaborative rich-text editor. Doesn't do spreadsheets or presentations or [...].
- Not E2EE (you need to trust that the server a bit more).
- Lightweight, works on slower connections, works alright on mobile. (1.7 MiB page transfer)
- Self-hosting quite simple.
PrivateBin:
- Super-simple plain-text/markdown pastebin. No editing possible once saved.
- E2EE
- Very small. Works fine on slow connections and mobile. (0.2 MiB page transfer)
- Self-hosting very simple.
To be clear though: by E2EE here I mean browser-side encryption with zero-knowledge on the server side.
Etherpad is still encrypted in transit with https; only the server can snoop.
Cryptpad and other web-based E2EE services can still be completely compromised server-side by serving malicious code to the browser, and practically the user would never know.